Halogenated alkenones, such as 4-ethoxy-1,1,1-trifluoro-3-butenone (ETFBO), are building blocks in chemical synthesis, as disclosed, for example, in U.S. Pat. No. 5,708,175, incorporated herein by reference. These alkenones may be prepared by reacting an acid chloride with a vinyl ether in the presence of a base, as described in the aforementioned U.S. patent. For this reaction, the base may also be used in excess as a solvent.
WO 03/066558, incorporated herein by reference, discloses production of alkenones from vinyl ethers and acid halides or acid anhydrides in the presence of onium salts. In the case of trifluoroacetic anhydride addition to ethyl vinyl ether, both addition of ethyl vinyl ether to a reaction medium containing trifluoroacetic anhydride and addition of trifluoroacetic anhydride to a reaction medium containing ethyl vinyl ether are described.
WO 2004/108647, incorporated herein by reference, discloses a simplified production of alkenones comprising addition of carboxylic acid halides to vinyl ethers. In the examples, trifluoroacetyl chloride is added to ethyl vinyl ether.